Equal catch size gave no clear warmth slope change for beetle richness in England and Scotland in 1993-2015

We tested whether fixed catch size changed the link between warmth and recorded beetle richness. We used 1,311 selected ten-trap collections in England and Scotland in 1993-2003 and 2004-2015. Models controlled location by calendar month, year, rain, collection duration and date. Observed minus 20-individual richness slopes were +0.008, -0.003, +0.241 and +0.314 taxon codes per degree C. All four adjusted year-cluster intervals included zero. Fixed samples of 10 or 30 individuals and shorter intervals also gave intervals across zero. Removing year effects gave a positive difference in later England. The results do not show a common slope change or prove that capture bias is absent. Few Scottish collections, coarse weather, quality and catch-size selection, taxon codes and correlated years limit inference. This is a measurement test, not a causal climate or air pollution test. The package gives code, source hashes, aggregate model evidence, checks and a figure. External raw and record-level data remain outside the bundle.

carabid beetles · temperature · taxon richness · rarefaction · observation bias · regional comparison · null result